Friday 8 January 2021 — Monthly Summary for Australia — Product Code IDCKGC1A00

Australia in December 2020

Temperatures Rainfall Extremes Important notes the top

In brief

• Mean maximum temperatures for December were warmer than average for the west of Western Australia and for the east coast of Queensland; cooler than average for most of the remainder of Western Australia, and most of the Northern Territory and South Australia
• Mean minimum temperatures for December were warmer than average for the west of Western Australia, Queensland, the east of the Northern Territory, northern and coastal New South Wales; cooler than average for much of the Kimberley, and part of inland southeast Australia
• Rainfall was very much above average for Australia overall; Australia's fourth-wettest December
• Rainfall for the month was above average in northern and eastern Western Australia, large areas of South Australia, north-eastern New South Wales, northern and western Queensland, and most of the Northern Territory
• Rainfall was below average for parts of southwest Western Australia

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Temperatures

The national mean temperature for December was 0.14 °C warmer than average for Australia as a whole.

The mean maximum temperature was below average for December at −0.46 °C, and below average for the Northern Territory and all States except Queensland. The mean minimum temperature was above average for December at +0.73 °C, and highest on record for Queensland.

Maximum temperatures for December were below average across large areas of Australia as tropical lows during the middle third of the month brought heavy rain and cooler temperatures stretching from the Pilbara and Kimberley into South Australia. Mean maximum temperatures were below average for the eastern half of Western Australia and part of the Pilbara, most of the Northern Territory except parts of the Top End and northeast; most of South Australia, and areas of northwest New South Wales and the coast between the Hunter and Illawarra, southwest Victoria and far southeast South Australia, and Tasmania's north coast. For an area of the inland northeast of Western Australia the mean maximum temperature was the lowest on record for December.

The mean maximum temperature for December was warmer than average for the west coast of Western Australia and along the east coast of Queensland.

The mean minimum temperature for the month was above or very much above average for Queensland, eastern and southern parts of the Northern Territory, northern and coastal New South Wales, and most of the western half of Western Australia away from the south coast. Mean minimum temperatures were below average for much of the Kimberley and adjacent northern interior of Western Australia, a pocket on the central south coast of Western Australia, and a large area extending from far southeast South Australia through much of northern and inland Victoria to central southern and inland New South Wales.

A few stations near the west coast of Western Australia observed record low temperatures for December on the 1st, while a few stations in the north of Western Australia had record low daily maximum temperatures for December early in the month, associated with the passage of a tropical low. Some stations in the Kimberley and the Pilbara recorded their lowest December mean daily maximum temperature for the month as a whole.

Record high daily maximum or minimum temperatures for December were observed at a few stations in Queensland and New South Wales in early December. A number of stations in both Queensland and New South Wales had their highest December mean daily minimum temperature on record for the month as a whole.

A few stations in New South Wales had record low December daily maximum temperatures on the 21st, as did a few in the Northern Territory on the 23rd.

Temperature maps
	Mean	Anomaly	Deciles
Mean daily maximum temperatures
Mean daily minimum temperatures
Mean daily temperatures

Temperatures Rainfall Extremes Important notes the top

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Rainfall

December rainfall was the fourth highest on record for December for Australia as a whole.

Rainfall for the month was above or very much above average across most of Western Australia away from the southwest, the Northern Territory, most of pastoral South Australia, northern and western Queensland, the north-eastern quarter of New South Wales, and north-eastern Tasmania. There were areas of record-high totals for December in the Kimberley and northeastern New South Wales.

Rainfall was below average for parts of the south-western quarter of Western Australia, and scattered small areas in southeast South Australia, eastern Victoria, New South Wales' Riverina, and greater southeast Queensland.

A slow-moving low pressure system and trough near the southern Queensland coast brought widespread heavy rainfall, damaging winds, abnormally high tides and dangerous surf to the northern half of the New South Wales coast and southeast Queensland during the middle of December. Widespread three-day totals in excess of 300 mm were observed in areas of the Gold Coast Hinterland and New South Wales' Northern Rivers and Mid North Coast districts.

The New South Wales State Emergency Service received more than 1000 calls for help and the Queensland Fire and Emergency Services received more than 1500 calls for help. Flash and riverine flooding occurred in Gold Coast hinterland in southeast Queensland, and in the Tweed, Clarence, Richmond/Wilsons and Bellinger rivers in New South Wales. Strong winds contributed to coastal inundation and erosion as damaging storm surges coincided with king tides in northeast New South Wales and southeast Queensland.

A number of stations in Queensland observed their wettest December day on record during this event or in further showers and storms across much of the State in the last week of the month, or associated with monsoonal activity across the north and northwest shortly after mid-December. A number of stations went on to observe their highest total monthly rainfall on record for December, or highest total in at least 20 years.

In New South Wales a large number of stations had their highest December daily rainfall on record during this period around the middle of the month, or assocaited with another trough during the last third of the month. A very large number of stations in New South Wales had their wettest December on record, or for at least 20 years.

Tropical lows affected the west of the country just before mid-December and again later in the month, bringing torrential rain. A few stations in Western Australia had their wettest December day on record on 12 or 11 December. A number of stations had their wettest December on record, or for at least 20 years.

Thunderstorms and tropical activity brought heavy rainfall over parts of the northwest of Australia and the Northern Territory during the second half of the month. Several stations in the Northern Territory had their highest December daily rainfall on record in the last third of the month. A number went on to observe their highest total monthly rainfall on record for December.

A few stations in Tasmania had their highest December total rainfall on record, or highest total in at least 20 years.

Area-average rainfall
	Rank (of 121)	Average (mm)	Departure from mean	Comment
Australia	118	98.6	+94%	4th highest (record 110.3 mm in 2010)
Queensland	99	111.2	+36%
New South Wales	111	81.8	+64%
Victoria	54	36.3	−24%
Tasmania	83	111.8	+8%
South Australia	92	28.3	+55%
Western Australia	118	85.9	+194%	4th highest (record 98.2 mm in 1930)
Northern Territory	117	179.8	+145%	5th highest
Murray-Darling Basin	71	50.1	+10%

Rank ranges from 1 (lowest) to 121 (highest). A rank marked with ’=‘ indicates the value is tied for that rank. Departure from mean is relative to the long-term (1961–1990) average.

Rainfall maps
	Totals	Percentages	Deciles
Total rainfall

Temperatures Rainfall Extremes Important notes the top

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Australian weather extremes during December 2020
Hottest day	48.7 °C	at Birdsville Airport (Qld) on the 5th
Coldest day	1.9 °C	at Mount Thredbo AWS (NSW) on the 6th and 7th
Coldest night	−6.0 °C	at Perisher Valley AWS (NSW) on the 11th
Warmest night	33.3 °C	at Windorah Airport (Qld) on the 3rd
Wettest day	338.4 mm	at Lower Springbrook Alert (Qld) on the 13th

Temperatures Rainfall Extremes Important notes the top

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